1. Field of the Invention
The present invention relates to a cooling and dust collecting apparatus for a drilling machine tool, in particular, to a cooling and dust collecting apparatus for use with a drilling machine which cools a cutter and sucks and exhausting cutting chips and poisonous gas.
2. Description of the Related Art
Generally, drilling machines such as hand-type air drills are used along with their cooling and dust collecting apparatuses. These cooling and dust collecting apparatuses cool a drill and exhaust cutting chips which take place in a drilling operation.
In recent years, compound materials such as carbon fiber reinforced plastics (CFRP) have been widely used in various fields including aircraft production. When a compound material is machined, however, it may emit poisonous gas due to frictional heat generated between the compound material and the drill. If the poisonous gas scattered to working environment, it would be very hazardous to the workers. Thus, the poisonous gas should be exhausted so that it does not scatter to the working environment.
A cooling and dust collecting apparatus for use with a drilling machine which cools a drill and exhausts poisonous gas as well as cutting chips is disclosed in Japanese Patent Laid Open Publication No. 63-16910.
FIG. 11 shows the cooling and dust collecting apparatus for use with the drilling machine disclosed in the Japanese Patent Laid Open Publication No. 63-16910. A drill 3 is attached to a drilling machine 1 by a chuck 2. A telescopically expandable/shrinkable cylinder 4 is mounted around the drilling machine 1. The expandable/shrinkable cylinder 4 has a base cylinder 5 and a movable cylinder 6. The base cylinder 5 is detachably mounted on the drilling machine 1. The movable cylinder 6 is telescopically connected to the base cylinder 5.
As shown in FIGS. 11 and 12, the base cylinder 5 has a plurality of inner protrusions 7. The protrusions 7 fit to end portions of L-letter shaped grooves 8 defined on the drilling machine 1 and secured by securing members 9. Thus, the base cylinder 5 is fixed to the drilling machine 1. The base cylinder 5 is airtightly closed by a ring-shaped rubber packing 11 which fits to a ring-shaped groove 10 of the drilling machine 1.
A base portion, which is a joint portion, of the movable cylinder 6 is disposed in an intermediate chamber 12 of the base cylinder 5. The joint portion is tensioned by a spring 13 disposed in the intermediate chamber 12 so that the joint portion is placed in a most extended position. A plurality of pins 14 are disposed in the base cylinder and protrude in the intermediate chamber 12. The pins 14 fit to grooves 6a defined on the outer periphery of the movable cylinder 6 so as to limit the movable range of the movable cylinder 6. An O ring 15 seals the base cylinder 5 and the movable cylinder 6.
A forward end portion of the movable cylinder 6 branches out into a cylindrical guide 16 and an outer cylinder 17. A ring-shaped chamber 18 is defined between the cylindrical guide 16 and the outer cylinder 17. The outer diameter of the cylindrical guide 16 is slightly larger than that of the drill 3. An inlet opening 19 is defined on the outer cylinder 17. The inlet opening 19 is connected to the ring-shaped chamber 18. An outlet opening 20 is connected to an intermediate portion of the movable cylinder 6. A detachable transparent sleeve 21 is disposed at a forward end of the movable cylinder 6. As shown in FIG. 13, the transparent sleeve 21 fits to a guide hole 22a defined on a panel 22.
Next, the operation of the related art cooling and dust collecting apparatus for use with the drilling machine will be described.
As shown in FIG. 13, compressed air supplied from the outlet opening 20 flows between the drill 3 and the cylindrical guide 16, thereby cooling the drill 3. Thereafter, the compressed air exits to the ring-shaped chamber 18. The drill 3 cuts a workpiece 23 which is made of a composite material. The resultant cutting chips and poisonous gas are sucked and exhausted from the inlet opening 19.
The cutting chips and poisonous gas are trapped in the ring-shaped chamber 18 and sucked from the inlet opening 19. Thus, the cutting chips and poisonous gas are exhausted to the outside of the apparatus without leakage to the working environment.
However, in the related art cooling and dust collecting apparatus for use with the drilling machine, the distance between the cylindrical guide and the drill was small, compressed air was not sufficiently supplied. In addition, cutting chips and poisonous gas were sucked from the inlet opening partially connected to the ring-shaped chamber. In other words, since the cutting chips and poisonous gas were not sufficiently exhausted, they adversely resided in the apparatus.